Piston expander



w. COOMBS PI STON EXPANDER Filed Feb. 8, 1935 Frq Z WiHIam M. Coombs INVENTOR.

BY W

TTORNEY.

Patentecl Oct. 13, 1936 PATENT OFFICE PISTON EXPANDER;

William M. Coombs, Youngstown,' 0l1io, assignor to Naomi A. Coombs, Youngstown, Ohio Application February 8, 1935, Serial No. 5,633

4 Claims.

This invention relates to piston expanders.

The principal object of this invention is to provide a piston expander that will provide for a desired expansion of the skirt of an ordinary piston.

A further object is to provide a piston expander that will provide desired expansion to the skirt of an ordinary piston through the'struts of the piston.

With the foregoing and other objects in view which will appear as the description proceeds, the invention resides in the combination and arrangement of parts and in the details of construction hereinafter described and claimed, it being understood that changes in the precise embodiment of the invention herein disclosed, can be made Within the scope of what is claimed, without departing from the spirit of the invention.

The invention is illustrated in the accompanying drawing, wherein:

Figure 1 is a side elevation of an ordinary piston showing the T slot.

Figure 2 is a sideelevation of an ordinary piston showing the wrist pin bearings and struts and with the piston expander in place.

Figure 3 is a cross sectional view taken on line 3-3 of Figure 2 showing the piston expander in place.

Figure 4 is a perspective detail of the piston expander.

In the piston expanders known to the art the practice has been to provide a circular spring type that is placed in the lower portion of the piston skirt. This type of expander maintains a continuous expanding pressure on the lower portion of the piston skirt, often setting up an undesirable pressure on the cylinder walls and thus causing undue wear. This spring type of expander, being located in the lower portion of the piston skirt, provides most of its expansion in the lower portion of the piston'skirt, thereby leaving the center and upper portions of the piston skirt in a relatively unexpanded position. This causes an uneven shaped piston which accounts for rapid wear on the piston rings as well as cylinder walls.

In my invention I provide a piston expander that is placed in the upper portions of the piston struts. Thus the expanding action of my expander is directlyon the supporting struts of the piston skirt. This expanding action on the piston skirt is applied through the ordinary supporting members, thus providing an equal expansion on all parts of the piston skirt. In my expander the expansion is limited to the desired amount, there being no spring to continuously force the piston skirts outwardly. Thus it is possible, by using my invention, to reshape the piston through expanding the skirt to its original size or larger so that the piston will conform with any irregularities in the cylinder wall.

By referring to Figures 1 and 2 of the drawing it will be seen that there is shown an ordinary piston. This piston is provided with a piston skirt l, a usual T slot 2, piston ring grooves 3, Wrist pin bearings 4, and struts 5. It will also be seen that there is provided a plurality of openings These openings 6 are in all extended portion of smaller diameter in which are key slots 9,. This piston expander l is also provided with a threaded end portion l 0 adapted to receive a nut H. In operation the piston expander l is placed in the openings 6. The head. 8 is then turned until the desired expansion has taken place in the piston skirt I. By referring to Figure 2 it will be seen that there is provided a key member I2 which is passed through the key slots 9 of the expander 1. One end of this key member I2 is passed over the strut 5, while the other end is passed through an opening I 3 in the strut 5 which is provided for this purpose. These ends are then engaged, thus holding the expander l in a keyed position.

It is evident that the nut l l on the piston expander I should be so placed that portions of the piston structure hold it in a firm position.

What I claim is:-

1. The combination of a piston comprising a slotted piston skirt having parallel struts therein, said parallel struts having oppositely disposed openings, and a piston expander comprising a threaded bolt extending through said openings, a head on said bolt, a nut on the opposite end of said bolt adapted to fit against a strut of said piston, means for adjusting said piston expander while in position, substantially as described for the purpose set forth, and means for holding said piston expander in a keyed position.

2. A piston expander for adjusting the struts of a slotted skirt piston comprising a threaded bolt inserted through said struts, a head on said bolt, a nut on the opposite end of said bolt adapted to fit against astrut of said piston, means for adjusting said piston expander while in position,

substantially as described for the purpose set forth, and means for holding said piston expander in a keyed position.

3. The combination of a piston comprising a slotted piston skirt having parallel struts therein, said parallel struts having oppositely disposed openings, and a piston expander comprising a threaded bolt extending through said openings, a head on said bolt, an extended portion of smaller diameter on said head, said head having key slots therein in order that the bolt may be keyed in position, a nut on the opposite end of said bolt adapted to fit against a strut of said piston, said key slots providing means for adjusting said expander when not keyed in position, substantially as described for the purpose set forth.

4. A piston expander for adjusting the struts of a slotted skirt piston, said piston expander being positioned near the top of the struts and in an adjoining position to the slot in the piston skirt, said piston expander comprising a threaded bolt inserted through said struts, a head on said bolt, an extended portion of said head of smaller diameter, said head having key slots therein in order that the bolt may be held in a keyed position, a nut on the opposite end of said bolt adapted to fit against a strut of said piston, said key slots providing means for adjusting said expander when in position, substantially as described for the purpose set forth.

WILLIAM M. COOMBS. 

